Diazothioether heterocyclic compounds



United States Patent 3,192,194 DKAZQTHIUETHER HETERQCYCLKC 1 CGMPUUNDSMarian Burg, Metucheu, NJZ, assignor to E. 1. du Pont de Nernours andCernpany, Wilmington, Eek, a corporation of Delaware No Drawing. FiledDec. 1, 1961, Ser. No. 156,530 2 Claims. (Cl. 260-141) result in theformation of images without the need for a water or wet system. Lnassignees Burg and Cohen application Serial No. 831,700, filed August 5,1959, now U.S. 3,060,023, for example, compositions and elements usefulin a dry image transfer process are disclosed.

An object of this invention is to provide novel diazo heterocycliccompounds. Another object is to provide novel, improvedphotopolymerizable compositions. Still another object is to providenovel image-yielding photopolymerizable elements. Yet another object isto provide improved elements containing said diazo heterocycliccompounds. A further object is to provide such elements which can bepolymerized by visible light sources. Still further objects will beapparent from the following description of the invention.

The novel diazothioethcr heterocyclic compounds of this invention arerepresented by the formula:

wherein Y is a heterocyclic ring radical containing nitrogen selectedfrom the group consisting of 3-pyridyl, thiazolyl, oxazolyl, selenazolyland pyrryl, said radical being fused to the nucleus of an aryl compoundselected from the group consisting of unsubstituted and substitutedbenzene and naphthalene, said substituents being selected from the groupconsisting of alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbonatoms, carbalkoxy wherein the alkoxy group is of 1 to 4 carbon atoms,halogen and phenyl, and Y is a radical selected from the groupconsisting of 5- and 6-mernber heterocyclic rings containing up to 2hetero-atoms selected from the group consisting of nitrogen, oxygen,sulfur and selenium and from said heterocyclic rings which are fused tothe nucleus of anaryl compound selected from the group consisting ofunsubstituted and substituted benzene and naphthalene, said substituentsbeing selected from the group consisting of alkyl of 1. to 4 carbonatoms, alkoxy of 1 to 4 carbon atoms, carbalkoxy wherein the alkoxygroup is of 1 to 4 carbon atoms, halogen and phenyl. The preferreddiazothioether heterocyclic compounds are characterized by having anextinction coefiicient e above 10 in at least one region of the spectrumbetween 380 and 700 millimicrons. Specific compounds represented by theformula include 2 (Z-benzothiazolediazomercapto)benzothiazole,

2.-(6-methyl-2-benzothiazolediazomercapto) 6 methylbenzothiazole,2-(6-chloro-2-benzothiazolediazomercapto) quinoline, 2(3-quinolinediazomercapto)benzimidazole,

and 2-(Z-benzothiazolediazomercapto)thiazoline.

The novel 'diazo heterocyclic compounds, as described above, areextremely useful inconjunction with monocompositions. Thephotopolymerizable compositions comprise a non-gaseous ethylenicallyunsaturated compound containing at least one terminal ethylenic group,having a boiling point above 100 C. at normal atmospheric pressure,being capable of forming a high polymer by free-radical initiated,chain-propagating, addition p0- lymerization and 0.001 to 10 parts byweight per 100 parts by weight of said ethylenically unsaturatedcompound of said diazo heterocyclic compound. The diazo heterocycliccompound, which functions as a photoinitiator, may be used as the solephotoinitiator or in combination with other photoinitiators such aspolynuclear quinones, acyloin and acyloin ethers.

In a preferred element, 0.001 to 2 parts by weight per 100 parts byweight of the total weight of components of a thermal additionpolymerization inhibitor is present in the photopolymerizablecompositions.

The photopolymerizable compositions are utilized in image-yieldingelements comprising a support bearing a photopolymerizable stratum, saidstratum having a stick temperature greater than 18 C. and comprising atleast one ethylenically unsaturated compound of the type described aboveancl a diazo photoinitiator compound as described above.

The phctopolymerizable elements are particularly useful in imagetransfer processes conducted at room tem perature or at elevatedtemperatures (thermal transfer) depending, of course, on thephotopolymerizable com position utilized to form the stratum. Preferablythe photopolymerizable composition contains a viscositymodifying agentwhich can increase or decrease the viscosity of the composition to makeit easier to prepare coated polymerizable elements. Viscosity-modifyingagents include fillers, both inorganic and polymeric; plasticizers andhigh-boiling solvents. A particularly preferred agent is a thermoplasticpolymeric compound solid at C. which serves as a binder for themonomeric compound and diazo initiator. In order to utilize the elementin room temperature transfer processes, the photopolymerizable stratumpossesses a stick temperature greater than 18 C. but no greater than thetemperature of the room. The photopolymerizable composition useful atroom temperature comprises an ethylenically unsaturated compoundcont'aining at least one terminal ethylenic group and the initiator aspreviously described. The thermoplastic compound solid at 50 C. can bepresent in combination with an amount of a viscosity modifier, e.g., 2to generally 2 to 50% by weight, based on the Weight of theethylenically unsaturated compound.

In order to protect all embodiments of the elements from the effects ofoxygen inhibition, they preferably have placed on theirphotopolymerizable stratum a cover sheet such as is described inassignees Heiart applications Serial No. 81,377, filed January 9, 1961,now US. 3,060,026, and Serial No. 123,651, filed July 13, 1961, and inassignees Burg application entitled Elements and Processes, Serial No.156,538 (now abandoned), filed even date herewith.

The photopolymerizable stratum of the above-described elements isexposed imagewise with visible and/or ultraviolet radiation, preferablyvisible, e.g., within the range of 380 to 700 millimicrons, so that theexposed image areas are polymerized with a subsequent increase in thestick temperature with substantially less polymerization and lessincrease in stick temperature in the underexposed, complementary,adjoining coplanar image areas to provide a difference of at least 10 C.in the stick temperature between said exposed and underexposed areas. Bybringing the exposed stratum into intimate contact, preferably underpressure, with an image-receptive support, e.g.,

paper, at the operating temperature, and separating the two surfaces, animage corresponding to the underexposed image areas is transferred tothe surface of the imagereceptive support. By such an exposure andtransfer operation; at least one copy of the original image can beobtained. Multiple copies can be obtained by repeating the transferprocedure using appropriate coating thicknesses of the stratum,pressures and temperatures to give thedesired number of copies. Pressurecan be applied by means well known to the art, e.g., rollers, flat orcurved surfaces or platens, etc. The contact time ranges from 0.01 to 10seconds, about 0.1 second, in general, being preferred. Shorter periodsof contact are possible, however, since time is not critical.

The term underexposed as used herein is intended to cover the imageareas which are completely unexposed or those exposed only to the extentthat there is addition polymerizable compound still present insuflicient quantity that the softening temperature remains substantiallylower than that of the complementary exposed image areas. The term sticktemperature, as applied to either an underexp'osed or exposed area of aphotopolymer-izable stratum, means the temperature at which the imagearea is question sticks or adheres (transfers), within 5 seconds, underslight pressure, e.g., thumb pressure, to analytical paper (Schleicherand Schull analytical filter paper No. 595 and remains adhered in alayer of at least detectable thickness after separation on theanalytical paper from the stratum. The term operating temperature meansthe temperature at which the operation of transferring the image fromthe photopolymerizable stratum to the image-receptive surface isactually carried out. The operating temperature is intermediate betweenthe stick temperatures of the underexposed and exposed areas of aphotopolymerizable stratum. The operating temperature may be at roomtemperature in the case of elements having a composition which is liquidor tacky at room temperature. The operating temperature 'may be as highas 220 C. for the thermal transfer operation.

Imagewise exposure of the photopolymerizable element requires the use ofa light source rich in radiation in the visible and/or ultravioletregion of the spectrum.

For the diazo initiators of this invention the exposure is preferably inthe visible, e.g., between 380 and 700 millimicrons. Such light sourcesinclude ordinary tungsten lamps, fluorescent lamps, mercury arcs, carbonarcs, photofiood lamps, sunlamps, photoflash, etc. The sur faces of theexposing sources are customarily maintained at a distance of up to about20 inches or more from the photopolymerizable layer.-

Imagewise exposure in the above-described invention can be made throughastencil, line or halftone .or continuous tone negative or positive orother suitable transparency and can be either by contact or projectionexposure. Alternatively, reflectographic exposure tech niques may alsobe employed. Sufiicient imagewise exposure to actinic radiation is givenuntil substantial addition polymerization takes place in the exposedareas to form an addition polymer and significantly less polymerizationtakes place in the underexposed areas.

The photopolymerizable compositions of the elements useful in either theroom temperature or thermal transfer processes contain free-radicalinitiated, chain-propagating addition polymerizable ethylenicallyunsaturated monomeric compounds such as an alkylene or a polyalkyleneglycol diacrylate prepared from an allrylene glycol 0f'2 to 15 carbonsor a polyalkylene ether glycol of 1 to ether linkages, and thosedisclosed in Martin and Barney,- US. Patent 2,927,022, issued March 1,1960, e.g., those having a plurality of addition polymerizable ethyleniclinkages, particularly whenpresent as terminal linkages, and especiallythose wherein at least one and preferably most of such linkages areconjugated with a doubly bonded carbon, including carbon doubly bondedto carbon and to such heteroatoms as nitrogen, oxygen and sulfur.

Outstanding are such materials wherein the ethylenically unsaturatedgroups, especially the vinylidene groups, are conjugated with ester oramid structures. The following specific compounds are furtherillustrative of this class: unsaturated esters of alcohols, preferablypolyols and particularly such esters of the alphamethylene carboxylicacids, e.g., ethylene diacrylate, diethylene glycol diacrylate, glyceroldiacrylate, glycerol triacrylate, ethylene dimethacrylate,1,3-propanediol dimethacrylate, l, 2,4-butanetriol trimethacrylate,1,4-cyclohexanediol diacrylate, 1,4-benzenediol dimethacrylate,pentaerythritol triacrylate and trimethacrylate, pentaerythritoltetraacrylate and tetramethacrylate, dipentaerythritol hexaacrylate,1,3-propanediol diacrylate, 1,5-pentanediol dimethacrylate, thebis-acrylates and meth-acrylates of polyethylene glycols of molecularweight 200-1500, and the like; unsaturated amides, particularly those ofthe alphamethylene carboxylic acids, and especially those ofalphapmega-diainines and oxygen-interrupted omega-diamines, such asmethylene bis-acrylamide, methylene bis-methacrylamide, ethylenebismethacrylamide, 1,6-hexamethylene bis-acrylamide, diethylene triaminetrismethacrylamide, bis (gamma-methacrylamidopropoxy)ethanebeta-methacrylamidoethyl methacrylate, N- (beta-hydroxyethyl -beta-(methacrylamido ethyl acrylate and N,N bis (beta-methacrylyloxyethyl)acrylamide; vinyl esters such as divinyl succinate, divinyl adipate,divinyl .phthalate, divinyl terephthalate, divinylbenezene-1,3-disulfonate, and divinyl butane-1,4-disulfonate; styreneand derivatives thereof and unsaturated aldehydes, such as sorbaldehyde(hexadienal). An outstanding class of these preferred additionpolymerizable components are the esters and amides of alphamethylenecarboxylic acids. and substituted carboxylic acids with polyols andpolyamideswherein the molecular chain between the hydroxyls and aminogroups is solely carbon or oxygen-interrupted carbon. The preferredmonomeric compounds are difunctional, but monofunctional orpolyfunctional monomers can also be used. The amount of monomer addedvaries with the particular polymers used.

The ethylenic unsaturation can be present as an extralinear substituentattached to a thermoplastic linear polymer, such aspolyvinylacetate/acrylate, cellulose acetate/ acrylate, celluloseacetate/methacrylate, N-acrylyloxymethylpolyamide,N-methacrylyloxymethylpolyamide, al lyloxymethylpolyamide, etc., inwhich case the monomer and polymer function are combined in a singlematerial.

The photopolymerizable monomers listed above which are normally solidand non-tacky at room temperature can be used when they are present incombination with viscosity modifiers. which lower viscosity, e.g.,plasticizers or high-boiling solvents, so that they becomepressuretransferable at room temperature like the less viscous or tackymonomeric compounds. Suitable plasticizers include low molecular weightpolyalkylene oxides, ethers and esters, e.g., triethylene glycoldicaprylate, polypropylene glycol mono-n-butyl ether; andother esterssuch as phthalates, e.g., dibutyl phthalate; adipates, e.g., diisobutyladipate; sebacatcs, e.g., dimethyl sebacate. In addition, phosphates,e.g., tricresyl phosphate; amides and sulfon amides, e.g.,n-ethyl-p-toluenesulfonamide;-carbonates, e.g., bis(dimethylbenzyl)carbonate; citrates, e.g., triethyl citrate; glycerol esters, e.g.,glycerol triacetate; laurates, e.g., n-butyl laurate; oleates,stearates, etc., are also useful.

The diazo initiator compounds within the scope of this invention aregenerally synthesized by converting a Y-containing amine to itsdiazonium salt and then coupling it witha Y containing mercapto compoundaccording to the general reactions:

Reaction (1) above is discussed in detail in K. H. Saunders, TheAromatic Diazo-compounds and Their Technical Applications, Edward Arnold& Co., London, England (1949), pages 2 to 20. Reaction (2) above isdiscussed in the Saunders reference at page 192 and in H. Zollinger, A20and Diazo Chemistry, Interscience Publishers, New York, New York (1961),page 150.

Suitable amines containing the Y radical include: 2- aminobenzothiazole,Z-amino-dmethylbenzothiazole, 2- amino-6-ethylbenzothiazole,Z-amino-6-methoxybenzothiazole, 2-amino-6-ethoxybenzothiazole,2-amino-6-phenylbenzothiazole, 2-amino-6-chlorobenzothiazole, Z-amino-6-bromobenzothiazole, Z-amino-6-carbethoxybenzothiazole,Z-aminobenzselenazole, and other benzselenazoles corresponding to theabove benzothiazoles, 3-aminoquinoline, 3-amino-Z-methylquinoline,3-amino-2-phenylquinoline, 2-amino-benzoxazole,Z-amino-5-chlorobenzoxazole, 3-aminoindole, and 3-amino-2-phenylindole,etc.

Examples of mercapto compounds containing the Y radical include:Z-mercaptobenzothiazole, 2-mercapto-6- methyl-, 2-rnercapto-6-phenyl-,2-mercapto-6-..thoxy-; 2- mercaptothiazole, 2-mercapto-4-methyl-,2-mercapto-5- phenyl-, 2-rnercapto-4-phenyl-, 2-mercapto-4,5-dimethyl-;Z-mercapto-thiophene; Z-mercaptothiazoline; Z-mercaptopyridine,4-mercapto-, 3-mercapto-, S-mercapto-Z-methoxy-, 3-mercapto-2-ethoxy-;Z-mercaptoquinoline, Z-mercapto-, 4-mercapto-, 4-mercapto-2-methyl-,4-mercapto-2- pheny1-, 4-mercapto-2-ethoxy-; Z-mercaptooxazole; 2-mercaptoimidazole, 2-mercapto-1-methyl-, Z-mercapto-S- phenyl-,2-mercapto-4,5-dimethyl-; Z-mercaptobenzimidazole;2-mercaptobenzselenazole; 2-mercaptopyrazine; 2- mercapto-benzoxazole;Z-mercaptopyrirnidine, 2-mercapto-5-chloro-, 2-mercapto-4,6-dimethyl-,etc.

Suitable polymerization inhibitors that can be used inphotopolymerizable compositions include p-methoxyphenol, hydroquinone,and alkyl and aryl-substituted hydroquinones and quinones,tert-butylcatechol, pyrogallol, copper resinate, naphthylamnies,beta-napthol, cup

.rous chloride, 2,6-di-tert-butyl p-cresol, phenothiazine,

pyridine, nitrobenzene, dinitrobenzene, iodine, sulfur, ptoluquinone andchloranil.

The image-yielding photopolymerizable elements are preferably made bycoating or extruding a photopolymerizable composition as described aboveand a volatile solvent in the form of a thin film onto the surface of asuitable support to form a layer which, when dry, is from 0.00005 inchto 0.005 inch in thickness, preferably 0.0001 to 0.001 inch. Suitablesupport materials are stable at the operating temperatures used in theinstant invention. Suitable supports include those disclosed in US.Patent 2,760,863, glass, wood, paper (including Waxed or transparentizedpaper), cloth, cellulose esters, e.g. cellulose acetate, cellulosepropionate, cellulose butyrate, etc., and other plastic compositionssuch as polyamides, polyesters, etc. The support may have in or on itssurface and beneath the photopolymerizable stratum an antihalationlayer' as disclosed in said patent or other substrata needed tofacilitate anchorage to the base. The elements can be made by proceduresdescribed in the aforesaid patent. Met extrusion, solvent extrusion,reverse roll coating and skim coating techniques can be used. Doctorknives and air doctor knives can be used to form the coatings.

The image receptive support to which the image is transferred must alsobe stable at the operating temperatures. desired use for the transferredimage and on the adhesion of the image to the base. Suitable supportsinclude paper including bond paper, resin and clay sized paper, resincoated or impregnated paper, cardboard, metal sheets,

foils and meshes, e.g., aluminum, copper, steel, bronze 'etc., wood,glass, nylon rubber polyethylene terephthalate; regenerated cellulose,cellulose esters, e.g., cellulose acetate; silk, cotton, viscose rayonand metal fabrics or The respective support may have a hydrophilicsurface The particular support used is dependent on the ormay contain onits surface chemical compounds which react with compounds beingtransferred so as to produce differences in color, hydrophilicity orconducitivity between the exposed and underexposed areas or for improvedadhesion or brightening of the receptive support. The image-receptivesurface may be smooth, contain roughening agents such as silica, beperforated or be in the form of a mesh or screen.

and i-sophthalic acids, and (5) mixtures of copolyesters prepared fromsaid glycols and (i) terephthalic, isophthalic and sebacic acids and(ii) terephthalic, isophthalic, sebacic and adipic acids.

(B) Nylons or polyamides, e.g., N-methoxymethyl polyhexamethyleneadipamide;

(C) Vinylidene chloride copolymers, e.g., vinylidenechloride/acrylonitrile; vinylidene chloride/methylacrylate andvinylidene chloride/vinylacetate copolymers;

(D) Ethylene/vinyl acetate copolymers;

(E) Cellulosic ethers, e.g., methyl cellulose, ethyl cellulose andbenzyl cellulose;

(F) Polyethylene;

(G) Synthetic rubbers, e.g., butadiene/acrylonitrile copolymers, andchloro-2-butadiene-1,3 polymers;

(H) Cellulose esters, e.g., cellulose acetate, cellulose acetatesuccinate and cellulose acetate butyrate;

(I) Polyvinyl esters, e.g., polyvinyl acetate/acrylate, polyvinylacetate/methacrylate and polyvinyl acetate;

(I) Polyacrylate and alpha-alkyl polyacrylate esters, e.g., polymethylmethacrylate and polyethyl methacrylate;

(K) High molecular weight polyethylene oxides of polyglycols havingaverage molecular weights from about 4,000'to 1,000,000;

(L) Polyvinyl chloride and copolymers, e.g., polyvinyl chlon'de/acetate;

(M) Polyvinyl acetal, e.g., polyvinyl butyral, polyvinyl formal;

(N) Polyformaldehydes;

(O) Polyurethanes;

(P) Polycarbonates;

(Q) Polystyrenes;

(R) Extralinear unsaturated polyamides, e.g., N-acrylyloxymethyl andN-methacrylyloxymethyl polyarnides.

To the thermoplastic polymer constituent of the photopolymerizablecomposition there can be added non-thermoplastic polymeric compounds toimprove certain desirable characteristics, e.g., adhesion to the basesupport, adhesion to the image-receptive support on transfer, wearproperties, chemical inertness, etc. Suitable non-thermoplasticpolymeric compounds include polyvinyl alcohol, cellulose, anhydrousgelatin, phenolic resins and melamineformaldehyde resins, etc. Ifdesired, the photopolyrnerizable layers can also contain immisciblepolymeric or non-polymeric organic or inorganic fillers or reinforcingagents which are essentially transparent at the wave lengths used forthe exposure of the photopolymeric material, e.g., the organophilicsilicas, bentonites, silica, powdered glass, colloidal carbon, as wellas various types of dyes and pigments. Such materials are used inamounts varying with the desired properties of the photopolymerizablelayer. The fillers are useful in improving the strength of thecomposition, reducing tack and, in addition, as coloring agents.

Various dyes, pigments, thermographic compounds and color-formingcomponents. can be added to the photopolymerizable compositions to givevaried results after the transfer step. These added materials,preferably,

should not absorb excessive amounts of radiation at the exposure wavelength or inhibit the polymerization reaction;

Among the dyesuseful in the invention are Acid Violet RRL (CI 42425),Red Violet SRS (CI 42690), Night Green B (CI 42115), CI Direct Yellow 9(CI 19540), CI Acid Yellow 17 (CI 18965), CI Acid Yellow 29 (CI 18900),Tartrazine (CI 19140), Supramine Yellow G (CI 19300), Buffalo Black 108(CI 27790), Naphthalene Black 12R (CI 20350), Safranine Bluish (CI BasicViolet 5), Auramine (CI Basic Yellow 2), Rhodamine 6GDN (CI Basic Red1), Azosol Fast Black MA (CI Solvent Black 19), and Methylene Violet (CIBasic Violet 5).

Suitable pigments include, e.g., TiO colloidal carbon, graphite,phosphor particles, ceramics, clays, metal powders such as aluminum,copper, magnetic iron and bronze, etc. The pigments are useful whenplaced in the photosensitive layer or in an adjacent nonphotosensitivelayer.

Useful 'thermographic additives, e.g.,3-cyano-4,5-dimethyl-S-hydroxy-3-pyrrolin-2-one are disclosed in Howard,US. Patent 2,950,987. Such compounds, in the presence of activators,e.g., copper acetate, are disclosed in assignees Belgian Patent 588,328.Other useful thermographic additives are disclosed in the following US.patents: 2,625,494; 2,637,657; 2,663,654; 2,663,655; 2,-

663,656; and 2,663,657.

Suitable color-forming components which form colored compounds on theapplication of heat or when brought in contact with other color-formingcomponents on a separate support include (1) Organic and inorganiccomponents: dimethyl gly- I oxime and nickel salts; phenolphthalein andsodium hydroxide; starch/potassium iodide and oxidizing agent, i.e.,peroxides; phenols and iron salts; thioacetamide and lead acetate;silver salt and reducing agent, e.g., hydroquinone.

(2) Inorganic components: ferric salts. and potassiumthiocyanateyferrous salts and potassium ferricyanide; copper, mercury orsilver salts and sulfide ions; lead acetate and sodium sulfide.

I (3) Organic components: 2,4-dinitrophenylhydrazine' and aldehydes' rketones; diazonium salt and phenol or naphthol, e.g., benzenediazoniumchloride and B-naphthol; substituted aromatic aldehydes or amines and acolor photographic developer compound, e.g., p-diethylaminobenzaldehydecolor photographic developer compound/ active methylene compound and anoxidizing agent, e.g., p-diethylaminotoluidine/ts-cyanoacetophenone andpotassium persulfate.

The invention will be further illustrated by but is not I intended to belimited to the following detailed proce dure and examples.

V PROCEDURE A 2- (Z-benzothiazolediazomercaptc) benzoflziazole Four anda half grams (0.03 mole) of 2-aminobenzothiazole in 25 -ml.,glacialacetic acid was diazotized at 5 to 8 C. by gradually adding 2.1 g.-(0.03 mole) of sodium nitrite dissolved in 5 ml. concentrated sulfuricacid at 0 C. When addition was completed, the reaction mixture wasallowed to remain at room temperature I for /2 hr. andwas added to amixture of 5.0 g. (0.03

mole). of Z-mercaptobenzothiazole, 100 ml. ethanol, 50 g.

a of hydrated sodium acetate and 100 ml. water. The resultingyellow-orange mixture was diluted with water, filtered and the solidwas; air dried. A benzene soluble I, portion was removed by extractingwith several portions of warm (50 C.) benzene. The combined benzeneexand p-diethylaminoaniline;

tracts were concentrated at room temperature to an orange red solidwhich was washed with a small amount 0f cold benzene to remoi e a redcolored impurity. The

resulting orange yellow solid was purified by dissolving in benzene andprecipitating by adding low boiling petroleum ether to the turbiditypoint and then chilling in an ice bath. An orange yellow solid, MP.122l24 C.

(with decomposition), was obtained, A max.=395 m e=l.3 x10 (cyclohexane)EXAMPLE I beverage blender 90 g. of polyethylene glycol diacrylate,

60 g. of cellulose acetate butyrate and 350 g. of acetone. The celluloseacetate butyrate contained ca. 20.5% acetyl groups, ca. 26% butyryl andca. 2.5% hydroxyl groups and had a viscosity of 9 to 13.5 poises asdetermined by ASTM method D-l343 in solution described as Formula A,ASTM method D-87 l-54T. The polyethylene glycol diacrylate was derivedfrom polyethylene glycol with an average molecular weight 7 of 300. Thesolution was brought up to 20 g. with acetone and coated under subduedlighting on a 0.00l-inch thick polyethylene terephthalate film base and,after drying to a thickness of 0.0003 inch, a similar sheet ofpolyethylene terephthalate film base was laminated over the coating bypressing at room temperature with a rubber squeegee. Two samples of thecoating were exposed through a transparency bearing a line image to aMacbeth l40-ampere, high carbon are light source at a distance of 15inches for two seconds. After exposure, the element was delaminated, washot pressed on bond paper, and the film base. bearing the adheringpolymerized material was separated while still hot to leave a clear bluepositive copy on thebond paper.

' EXAMPLE II A test solution consistingof 1.5 ml. of polyethylene glycoldiacrylate as described in Example I to which was added 0.05 or 0.01% byweight of an azo photoinitiator set forth below Was placed in a 1.5 cm.x 8 cm. Pyrex test tube and flushed. with nitrogen for five minutes.Exposure was made to an air-cooled 400-watt high pressure mercury arclamp, GET-1400411, at a distance of eight inches with the test tubebeing contained in a black lined box having a window with a Wratten 2Cfilter placed over it. Polymerization time was recorded as that timerequired for formation of a gel or polymer skin on the test tube wall.The sharp cutting Wratten 2C filter, with an optical density greaterthan 3.0 at wave lengths below 380 millimicrons, was eifective inremoving essentially all the ultraviolet radiation while passing most ofthe visible light. The Wratten 2C filter transmits 38% of the radiationat 400 millimicrons, 0.1% at 380 millimicrons.

Diazo initiator: Polymerization 2 (2 benzothiazolediazomer- Hard polymerin capto)benzothiazole 0.3 minute. Control (no initiator present) Nonein minutes.

In the above examples, the abbreviations CI refers to the Colour Index,2nd edition, The Society of Dyers and Colourists, Dean House, Picadilly,Bradford, Yorkshire, England, 1956, and The American Association of Textile Chemists and Colorists, Lowell Technological Institute, Lowell,Massachusetts, U.S.A.

As indicated above the photopolymerizableelements are useful in imagetransfer processes conducted at room temperature or at elevatedtemperatures. Such processes are useful for a variety of copying,printing, decorative and manufacturing applications. Multicopies of theprocess images can be obtained from the transferred image.

The number of copies prepared is dependent on the photopolymeriza-blecomposition thickness as well as the process conditions. The process isalso useful for preparing multicolor reproductions.

Lithographic surfaces can be produced by transferring a hydrophobiclayer to a hydrophilic receptor surface or a hydrophilic layer to ahydrophobic receptor surface. The images on the lithographic surface canbe made impervious to chemical or solvent attack by post-exposing thelithographic surface. Alternatively, the exposed areas of thephotopolymerizable composition, after the underexposed areas aretransferred, can be used as a 1it11ographic-offset printing plate ifthey are hydrophobic :and the original sheet support is hydrophilic orvice versa.

The transferred images are not only useful for making copies of theoriginal image transparency by dry methods as indicated above but aftertransfer of the unde exposed areas to a receptor support, the exposedsurface can be treated with, e.g., aqueous solutions, dyes, inks, etc.,to form colored images. Colored copie of the original image can beobtained when the wet surface is brought into intimate contact with areceptor support and the surfaces separated. Solvents which are used forthe spirit copying, e.g., ethanol, water, should meter out the dye usedand be a non-solvent for'the polymer, i.e., the solubility of the dyeand binder are important factors in selecting the solvent.

The exposed photopolymerized stratum can be brought into intimatecontact at room temperature with a separate support, e.g., a roll ofcarbon or graphite; a roll coated with pigment dispersions; a roll whichhas a continuously replenished pigment or inked surface; a separatesupport coacted with pigments with or without dyes, color formingcompounds, hydrophilic and hydrophobic surfaces or a metallized Uponremoving the surfaces, the areas corresponding to the underexposed areasof the photopolymerized composition are transferred. A duplicate copyand a reverse copy are formed simultaneously.

The exposed photopolymerized surfaces are also useful with variousdusting techniques, e.g., with finely divided dyes and pigments, thematerials adhering in the underexposed areas. Multiple copies can beprepared. The dusted films are useful .as filters, in the preparation oflithographic printing plates by using hydrophilic or hydrophobicmaterials, in the manufacture of printed circuits and electricallyconducting or photoconductive matrices, in the preparation of two andmulticolor reproductions :and phosphor and ceramic patterns.

In addition to the above uses, the novel diazo initiators are useful inother processes involving development of an image, e.g., in preparingrelief printing plates or offset plates wherein solvent removal ofunpolymerized material might be used. Thus these elements would beuseful in processes such as described in Plambeck US. Patent 2,760,863and in Martin et al., US. Patent 2,927,022. The diazo initiators, ofcourse, are useful in bulk, emulsion, etc., type polymerizations of thedisclosed monomers.

An advantage of the diazo initiators herein employed is their relativelygreat solubility. The ability to work with reasonably concentratedsolutions of the initiator is desirable. Another advantage of theinvention is that the compositions and elements containing the diazoinitiators can in many cases be exposed by visible light. Thus, theexposing light source may be simple and inexpensive, such as tungsten orfluorescent lamps. A further advantage of this invention is that manydifferent types of image-receptive surfaces, as described previouslyabove, can be used, i.e., any readily available uncoated paper willserve satisfactorily. Yet a further advantage is the ease of makingmultiple copies. Many other advantages will be apparent from the abovespecification.

What is claimed is:

1. An diazothioether heterocyclic compound of the formula:

wherein Y is a heterocyclic ring radical containing nitrogen selectedfr-om the group consisting of 3-pyridyl, thiaz olyl, oxazolyl,selenazolyl and pyrryl, said radical being fused to the nucleus of an'aryl compound selected from .the group consisting of unsubstituted andsubstituted benzene and naphthalene, said substituents being selectedfrom the group consisting of alkyl of l to 4 carbon atoms, alkoxy of 1to 4 carbon atoms, carbalkoxy wherein the alkoxy group is of 1 to 4carbon atoms, halogen and phenyl, and Y is a radical selected from thegroup consisting of a 5- and G-member hete-rocyclic ring containing upto 2 heteroatoms selected from the group consisting of nitrogen, oxygen,sulfur and selenium and said heterocyclic ring being fused to thenucleus of an aryl compound selected from the group consisting ofunsubstituted and substituted benzene and n-athalene, said substituen-tsbeing selected from the group consisting of alkyl of 1 to 4 carbonatoms, alko-xy of 1 to 4 carbon atoms, carbalkoxy wherein the alkoxygroup is of l to 4 carbon atoms, halogen and phenyl.

2. 2-('2-benzothiazolediazomercapto)benzothianole.

References Cited by the Examiner UNITED STATES PATENTS 2,540,011 1/51Reynolds et a1. 260-441 2,540,057 '1/5l Sprung et al. 26014l 2,658,876 11/53 Reynolds 260--2.5 2,893,868 7/59 Barney 96l15 2,972,540 2/ 6-1Saner et a1, 96-1l5 OTHER REFERENCES Reynolds et .al.: Ind. and Eng.Chemistry, vol 42, No. 9, pages 1905- 10, September 1950.

CHARLES B. PARKER, Primary Examiner.

1. AN DIAZOTHIOETHER HETEROCYCLIC COMPOUND OF THE FORMULA: